--- winsup/cygwin/include/sys/termios.h.orig	2005-05-01 20:50:10.000000000 -0700
+++ winsup/cygwin/include/sys/termios.h	2005-08-01 02:22:34.361969600 -0700
@@ -1,6 +1,6 @@
 /* sys/termios.h
 
-   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2003 Red Hat, Inc.
+   Copyright 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2005 Red Hat, Inc.
 
 This file is part of Cygwin.
 
@@ -14,6 +14,8 @@ details. */
 #define _SYS_TERMIOS_H
 
 #define	TIOCMGET	0x5415
+#define	TIOCMBIS	0x5416
+#define	TIOCMBIC	0x5417
 #define	TIOCMSET	0x5418
 #define	TIOCINQ		0x541B
 
--- winsup/cygwin/fhandler.h.orig	2005-07-29 10:04:46.000000000 -0700
+++ winsup/cygwin/fhandler.h	2005-08-01 11:46:07.884528000 -0700
@@ -722,6 +722,7 @@ class fhandler_serial: public fhandler_b
   int tcdrain ();
   int tcflow (int);
   int ioctl (unsigned int cmd, void *);
+  int switch_modem_lines (int set, int clr);
   int tcsetattr (int a, const struct termios *t);
   int tcgetattr (struct termios *t);
   _off64_t lseek (_off64_t, int) { return 0; }
--- winsup/cygwin/fhandler_serial.cc.orig	2005-07-06 13:05:00.000000000 -0700
+++ winsup/cygwin/fhandler_serial.cc	2005-08-01 11:50:49.269139200 -0700
@@ -376,6 +376,56 @@ fhandler_serial::tcflow (int action)
 }
 
 
+/* switch_modem_lines: set or clear RTS and/or DTR */
+int
+fhandler_serial::switch_modem_lines (int set, int clr)
+{
+  int res = 0;
+
+  if (set & TIOCM_RTS)
+    {
+      if (EscapeCommFunction (get_handle (), SETRTS))
+        rts = TIOCM_RTS;
+      else
+        {
+          __seterrno ();
+          res = -1;
+        }
+    }
+  else if (clr & TIOCM_RTS)
+    {
+      if (EscapeCommFunction (get_handle (), CLRRTS))
+        rts = 0;
+      else
+        {
+          __seterrno ();
+          res = -1;
+        }
+    }
+  if (set & TIOCM_DTR)
+    {
+      if (EscapeCommFunction (get_handle (), SETDTR))
+        rts = TIOCM_DTR;
+      else
+        {
+          __seterrno ();
+          res = -1;
+        }
+    }
+  else if (clr & TIOCM_DTR)
+    {
+      if (EscapeCommFunction (get_handle (), CLRDTR))
+        rts = 0;
+      else
+        {
+          __seterrno ();
+          res = -1;
+        }
+    }
+
+  return res;
+}
+
 /* ioctl: */
 int
 fhandler_serial::ioctl (unsigned int cmd, void *buffer)
@@ -432,44 +482,17 @@ fhandler_serial::ioctl (unsigned int cmd
 	  }
 	break;
       case TIOCMSET:
-	if (ipbuffer & TIOCM_RTS)
-	  {
-	    if (EscapeCommFunction (get_handle (), SETRTS))
-	      rts = TIOCM_RTS;
-	    else
-	      {
-		__seterrno ();
-		res = -1;
-	      }
-	  }
-	else
-	  {
-	    if (EscapeCommFunction (get_handle (), CLRRTS))
-	      rts = 0;
-	    else
-	      {
-		__seterrno ();
-		res = -1;
-	      }
-	  }
-	if (ipbuffer & TIOCM_DTR)
-	  {
-	    if (EscapeCommFunction (get_handle (), SETDTR))
-	      dtr = TIOCM_DTR;
-	    else
-	      {
-		__seterrno ();
-		res = -1;
-	      }
-	  }
-	else if (EscapeCommFunction (get_handle (), CLRDTR))
-	  dtr = 0;
-	else
-	  {
-	    __seterrno ();
-	    res = -1;
-	  }
+        if (switch_modem_lines (ipbuffer, ~ ipbuffer))
+          res = -1;
 	break;
+      case TIOCMBIS:
+	if (switch_modem_lines (ipbuffer, 0))
+          res = -1;
+        break;
+      case TIOCMBIC:
+	if (switch_modem_lines (0, ipbuffer))
+          res = -1;
+        break;
       case TIOCCBRK:
 	if (ClearCommBreak (get_handle ()) == 0)
 	  {